Benjamin Rogers, who plays the shopkeeper, appeared previously in the Season 1 episode Hook Man (2005). Sam and Dean make a reference to this by mentioning that they met him in a case located in Auburn involving witches.
When Gadreel asks for griffin feathers in a shop, the shopkeeper tells him "This ain't Diagon Alley". This is a reference to Harry Potter; Diagon Alley is an area full of shops including those that sell magical items.
In the scene where Castiel is talking to Sam and Dean about related crimes, a picture of Jason Fischer (the guy with the glasses) is on the wall. Fischer is a Production Coordinator for the show.
Ogden, Utah exists; however, neither Bishop's Falls nor Auburn exist in Utah.
Erica Carroll (who plays the angel Hannah) previously appeared in two episodes; Faith (2006) (as Nurse) and Something Wicked (2006) (as Young Mother).